It is striking when a very detailed and complex set of symptoms crop up in patients across history and around the world. One is Capgras syndrome, in which the patient believes that a loved one has been replaced by an identical-looking imposter.
A UC-San Diego neurologist, V.S. Ramachandran, hypothesized what might cause such a wild syndrome. One tiny part of the brain identifies faces, and another associates certain feelings with faces. In these patients, the connection between these two parts of the brain appears to have been damaged, so that the patient identifies a face as familiar but fails to associate any emotion with it. This creates a mental disconnect ("I see my wife but it generates no emotion"), and it seems that the brain's way of reconciling this mental issue is by convincing itself that the person they are seeing looks like their loved one but is an imposter. Ramachandran did some interesting laboratory experiments that strongly support his hypothesis.
The idiosyncracies of our behavior can be affected by the slightest physical changes in our brains.
